Many different types of yarns made of natural fibers are known in the art. One well known example is paper yarn, which is traditionally manufactured from paper sheets. Typically, paper yarns are made from paper by first cutting the paper to narrow strips. These strips are then twisted to produce one paper yarn filament. These filaments are reeled to big reels and post processed to give different end properties. After this yarns are spun to smaller reels and finally dried in special drying unit.
The paper yarn has limited applications because of deficiencies in its properties, such as limited strength, unsuitable thickness, layered or folded structure, and further, the manufacturing method is inefficient.
In manufacturing paper yarn, the wet extrusion nozzle plays a key role in fiber orientation and in crosslinking of the fibers. However, to achieve the best possible yarn strength the fibers must be well twisted. Moreover, to improve the internal bonding of the fibers the fibers must be bonded together. The previous known solutions provide a nozzle having a diameter smaller than average fiber length which provides an upper limit to achievable yarn diameter. One such system and method has been disclosed in WO publication number 2013/0347814.
In this WO '814 publication a system and a method for manufacturing a fibrous yarn is disclosed. The method and system involves providing an aqueous suspension comprising fibers and a rheological modifier. The suspension provided is passed through a nozzle and then dewatered using a dewatering system.
The dewatering system disclosed in the process, however, created undue stresses on the paper yarn. These undue stresses more often result in breakage of the yarn during twisting and dewatering processes.
Another document U.S. Pat. No. 8,945,453 discloses method for producing polytetrafluoroethylene fiber and polytetrafluoroethylene fiber. The '453 patent document discloses a nozzle structure adapted to produce a polytetrafluoroethylene fiber from an aqueous suspension. However, the '453 patent document does not provide any solution for enhancing the strength of natural fibrous yarn so that the breakage of the yarn during the dewatering process can be avoided.
Accordingly, there is a need for controlling the yarn strength so that the breakage of the yarn could be avoided during the twisting and the dewatering processes. Further, there is a need for a device and a way to successfully deliver fiber yarn to the dewatering or the drying section of the process.
Furthermore, there is a need to use the knowledge on the structure and dynamics of the materials and their reactions to allow continuous production of fibrous yarn, in such processes. Moreover, a precise control of operational conditions (physical conditions: temperature, pressure, velocity, dwelling time; chemical conditions: pH, concentrations) has to be found.